A rechargeable battery (storage battery) such as a lithium-ion rechargeable battery, for example, is used to be mounted on a ship, a railway vehicle, a motor vehicle, and the like, is used for leveling electric power obtained from renewable energy, and is used in a smart grid. In particular, the lithium-ion rechargeable battery is suitable for the above use because the lithium-ion rechargeable battery is small and has a high power density. In a case where the rechargeable battery is applied to the above use, a large battery capacity and a high battery voltage are usually demanded. In view of this, by assembling a plurality of single cells (battery cells) which are rechargeable batteries to forma battery module, the rechargeable batteries are usually used in the form of a battery pack including the battery module.
Battery characteristics of a rechargeable battery, such as a battery capacity and a battery voltage, are different depending on a temperature of the rechargeable battery. In particular, the battery characteristics are usually decreased as the temperature of the rechargeable battery is increased. Therefore, it is desirable that the battery temperature that may be increased during charging/discharging of the rechargeable battery be decreased by cooling or the like.
In a case where a plurality of single cells are assembled and used (e.g., in a case where the single cells are used in the form of a battery module or a battery pack), it is desirable to cool the single cells and reduce a temperature difference between the single cells. If the temperature difference between the single cells is increased, the battery characteristics become different between the single cells. Because a capacity of a whole battery is limited by a short-life cell, the battery characteristics of the whole battery module, the whole battery pack, or the like are decreased.
In view of this, there is known a technique for reducing, in a battery provided by assembling a plurality of single cells, a temperature difference between the single cells. Specifically, PTL 1 describes a storage battery in which a battery container housing power generation elements of single cells has a rectangular parallelepiped having short side surfaces having a narrow width and long side surfaces having a wide width, the storage battery being provided as an assembled battery having a necessary electric power capacity by connecting the plurality of single cells adjacent to each other between the short side surfaces of the battery container.